Linux distribution based on free and open-source software From Wikipedia, the free encyclopedia
Debian (/ˈdɛbiən/),[7][8] also known as Debian GNU/Linux, is a free and open source[b] Linux distribution, developed by the Debian Project, which was established by the late Ian Murdock in August 1993. Debian is one of the oldest operating systems based on the Linux kernel, and is the basis of many other Linux distributions.
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![]() Debian 12 (Bookworm) running its default desktop environment, GNOME Version 43.9 | |
Developer | The Debian Project |
---|---|
OS family | Linux (Unix-like) |
Working state | Current |
Source model | Open source |
Initial release | August 1993[1] |
Latest release | 12.9[2] / January 11, 2025 |
Repository | salsa.debian.org |
Available in | 78 languages |
Update method |
|
Package manager | APT, dpkg |
Platforms | |
Kernel type | Monolithic (Linux kernel) |
Userland | GNU |
Default user interface | GNOME[a] |
License | DFSG-compatible licenses, plus proprietary firmware files |
Official website | www |
As of September 2023, Debian is the second-oldest Linux distribution still in active development: only Slackware is older. The project is coordinated over the Internet by a team of volunteers guided by the Debian Project Leader and three foundational documents: the Debian Social Contract, the Debian Constitution, and the Debian Free Software Guidelines.
In general, Debian has been developed openly and distributed freely according to some of the principles of the GNU Project and Free Software.[9][11] Because of this, the Free Software Foundation sponsored the project from November 1994 to November 1995.[12] However, Debian is no longer endorsed by GNU and the FSF because of the distribution's long-term practice of hosting non-free software repositories and, since 2022, its inclusion of non-free firmware in its installation media by default.[9][10] On June 16, 1997, the Debian Project founded the nonprofit organization Software in the Public Interest to continue financing its development.
Debian distribution codenames are based on the names of characters from the Toy Story films. Debian's unstable trunk is named after Sid, a character who regularly destroyed his toys.[13]
First announced on August 16, 1993, Debian was founded by Ian Murdock, who initially called the system "the Debian Linux Release".[14][15] The word "Debian" was formed as a portmanteau of the first names of himself and his then-girlfriend (later ex-wife) Debra Lynn.[16] Before Debian's release, the Softlanding Linux System (SLS) had been a popular Linux distribution and the basis for Slackware.[17] Murdock was motivated to launch a new distribution by what he saw as poor maintenance and the prevalence of bugs in SLS.[18]
Debian 0.01, released on September 15, 1993, was the first of several internal releases.[19] Version 0.90 was the first public release,[19] supported through mailing lists hosted at Pixar.[20] The release included the Debian Linux Manifesto, outlining Murdock's view for the new operating system. In it he called for the creation of a distribution to be maintained "openly in the spirit of Linux and GNU."[21]
The Debian project released the 0.9x versions in 1994 and 1995.[22] During this time it was sponsored by the Free Software Foundation for one year.[23] Ian Murdock delegated the base system, the core packages of Debian, to Bruce Perens, while Murdock focused on the management of the growing project.[18] The first ports to non-IA-32 architectures began in 1995, and Debian 1.1 was released in 1996.[24] By that time and thanks to Ian Jackson, the dpkg package manager was already an essential part of Debian.[25]
In 1996, Bruce Perens assumed the project leadership. Perens was a controversial leader, regarded as authoritarian and strongly attached to Debian.[26] He drafted a social contract and edited suggestions from a month-long discussion into the Debian Social Contract and the Debian Free Software Guidelines.[27] After the FSF withdrew their sponsorship in the midst of the free software vs. open source debate,[28] Perens initiated the creation of the legal umbrella organization Software in the Public Interest instead of seeking renewed involvement with the FSF.[24] He led the conversion of the project from the a.out to the ELF executable format.[18] He created the BusyBox program to make it possible to run a Debian installer from a single floppy disk, and wrote a new installer.[29] By the time Debian 1.2 was released, the project had grown to nearly two hundred volunteers.[18] Perens left the project in 1998.[30]
Ian Jackson became the project leader in 1998.[31] Debian 2.0 introduced the second official port, m68k.[22] During this time the first port to a non-Linux kernel, Debian GNU/Hurd, was started.[32] On December 2, the first Debian Constitution was ratified.[33]
From 1999, the project leader was elected yearly.[34] The number of applicants was overwhelming and the project established the new member process.[35][36] The package manager front-end APT was deployed with Debian 2.1.[22] The first Debian derivatives, namely Libranet,[37] Corel Linux and Stormix's Storm Linux, were started in 1999.[24] The 2.2 release in 2000 was dedicated to Joel Klecker, a developer who had recently died of Duchenne muscular dystrophy.[38]
In late 2000, the project reorganized the archive with new package "pools" and created the Testing trunk, made up of packages considered stable, to reduce the freeze for the next release.[24] In the same year, developers began holding an annual conference called DebConf with talks and workshops for developers and technical users.[39] In May 2001, Hewlett-Packard announced plans to base its Linux development on Debian.[40]
In July 2002, the project released version 3.0, code-named Woody, the first release to include cryptographic software, a free-licensed KDE and internationalization.[41] During these last release cycles, the Debian project drew considerable criticism from the free software community because of the long time between stable releases.[42][43][44]
Some events disturbed the project while the Sarge release was in preparation, as Debian servers were attacked by fire and hackers.[24][45] One of the most memorable was the Vancouver prospectus.[46][47][48] After a meeting held in Vancouver, release manager Steve Langasek announced a plan to reduce the number of supported ports to four in order to shorten future release cycles.[49] There was a large reaction because the proposal looked more like a decision and because such a drop would damage Debian's aim to be "the universal operating system".[50][51][52]
The first version of the Debian-based Ubuntu distribution, named "4.10 Warty Warthog", was released on October 20, 2004.[53] Because it was distributed as a free download, it became one of the most popular and successful operating systems with more than "40 million users" according to Canonical Ltd.[54][55] However, Murdock was critical of the differences between Ubuntu packages and Debian, stating that it led to incompatibilities.[56]
The 3.1 Sarge release was made in June 2005. This release updated 73% of the software and included over 9,000 new packages. A new installer with a modular design, Debian-Installer, allowed installations with RAID, XFS and LVM support, improved hardware detection, made installations easier for novice users, and was translated into almost forty languages. An installation manual and release notes were in ten and fifteen languages respectively. The efforts of Skolelinux, Debian-Med and Debian-Accessibility raised the number of packages that were educational or had a medical affiliation, and of packages made for people with disabilities.[24][57]
In 2006, as a result of a much-publicized dispute, Mozilla software was rebranded in Debian. The Mozilla Corporation stated that software with unapproved modifications could not be distributed under the Firefox trademark. Two reasons that Debian had modified the Firefox software were to replace non-free artwork and to provide security patches.[58][59] Consequently, Debian contained a fork of Firefox named Iceweasel and one of Thunderbird named Icedove. In February 2016, it was announced that Mozilla and Debian had reached an agreement and Iceweasel would revert to the name Firefox; a similar agreement was anticipated for Icedove/Thunderbird.[60]
A fund-raising experiment, Dunc-Tank, was created to solve the release cycle problem and release managers were paid to work full-time;[61] in response, unpaid developers slowed down their work and the release was delayed.[62]
Debian 4.0 (Etch) was released in April 2007, featuring the x86-64 port and a graphical installer.[22]
Debian 5.0 (Lenny) was released in February 2009, supporting Marvell's Orion platform and netbooks such as the Asus Eee PC.[63] The release was dedicated to Thiemo Seufer, a developer who died in a car crash.[64]
In July 2009, the policy of time-based development freezes on a two-year cycle was announced. Time-based freezes are intended to blend the predictability of time based releases with Debian's policy of feature-based releases, and to reduce overall freeze time.[65] The Squeeze cycle was going to be especially short; however, this initial schedule was abandoned.[66] In September 2010, the backports service became official, providing more recent versions of some software for the stable release.[67]
Debian 6.0 (Squeeze) was released in February 2011, featuring Debian GNU/kFreeBSD as a technology preview, along with adding a dependency-based boot system, and moving problematic firmware to the non-free section.[68]
Debian 7 (Wheezy) was released in May 2013, featuring multiarch support.[69]
Debian 8 (Jessie) was released in April 2015, using systemd as the new init system.[70]
Debian 9 (Stretch) was released in June 2017, with nftables as a replacement for iptables, support for Flatpak apps, and MariaDB as the replacement for MySQL.[71][72]
Debian 10 (Buster) was released in July 2019, adding support for Secure Boot and enabling AppArmor by default.[73]
Debian 11 (Bullseye) was released in August 2021, enabling persistency in the system journal, adding support for driverless scanning, and containing kernel-level support for exFAT filesystems.[74]
Debian 12 (Bookworm) was released on June 10, 2023, including various improvements and features, increasing the supported Linux Kernel to version 6.1, and leveraging new "Emerald" artwork.[75] Debian 12 also was the first version under a revised Debian Social Contract that includes non-free firmware in its installation media by default, if and when the installer detects that it is needed for installed hardware to function, such as with Wi-Fi cards.[9][10]
Debian is still in development and new packages are uploaded to unstable every day.[76]
Debian used to be released as a very large set of CDs for each architecture, but with the release of Debian 9 (Stretch) in 2017, many of the images have been dropped from the archive but remain buildable via jigdo.[77]
Throughout Debian's lifetime, both the Debian distribution and its website have won various awards from different organizations,[78] including Server Distribution of the Year 2011,[79] The best Linux distro of 2011,[80] and a Best of the Net award for October 1998.[81]
On December 2, 2015, Microsoft announced that they would offer Debian GNU/Linux as an endorsed distribution on the Azure cloud platform.[82][83] Microsoft has also added a user environment to their Windows 10 desktop operating system called Windows Subsystem for Linux that offers a Debian subset.[84]
Debian has access to online repositories that contain over 51,000 packages.[85] Debian officially contains only free software, but non-free software can be downloaded and installed from the Debian repositories.[86] Debian includes popular free programs such as LibreOffice,[87] Firefox web browser, Evolution mail, K3b disc burner, VLC media player, GIMP image editor, and Evince document viewer.[86] Debian is a popular choice for servers, for example as the operating system component of a LAMP stack.[88][89]
Several flavors of the Linux kernel exist for each port. For example, the i386 port has flavors for IA-32 PCs supporting Physical Address Extension and real-time computing, for older PCs, and for x86-64 PCs.[90] The Linux kernel does not officially contain firmware lacking source code, although such firmware is available in non-free packages and alternative installation media.[91][92]
Debian offers CD and DVD images specifically built for Xfce, GNOME, KDE, MATE, Cinnamon, LXDE, and LXQt.[68] MATE support was added in 2014,[93] and Cinnamon support was added with Debian 8 Jessie.[94] Less common window managers such as Enlightenment, Openbox, Fluxbox, IceWM, Window Maker and others are available.[95]
The default desktop environment of version 7 Wheezy was temporarily switched to Xfce, because GNOME 3 did not fit on the first CD of the set.[96] The default for the version 8 Jessie was changed again to Xfce in November 2013,[97] and back to GNOME in September 2014.[98]
Several parts of Debian are translated into languages other than American English, including package descriptions, configuration messages, documentation and the website.[99] The level of software localization depends on the language, ranging from the highly supported German and French to the barely translated Creek and Samoan.[100] The Debian 10 installer is available in 76 languages.[101]
Multimedia support has been problematic in Debian regarding codecs threatened by possible patent infringements, lacking source code, or under too restrictive licenses.[102] Even though packages with problems related to their distribution could go into the non-free area, software such as libdvdcss is not hosted at Debian .[103]
A notable third party repository exists, formerly named Debian-multimedia.org,[104][105][106] providing software not present in Debian such as Windows codecs, libdvdcss and the Adobe Flash Player.[107] Even though this repository is maintained by Christian Marillat, a Debian developer, it is not part of the project and is not hosted on a Debian server. The repository provides packages already included in Debian, interfering with the official maintenance. Eventually, project leader Stefano Zacchiroli asked Marillat to either settle an agreement about the packaging or to stop using the "Debian" name.[108] Marillat chose the latter and renamed the repository to deb-multimedia.org. The repository was so popular that the switchover was announced by the official blog of the Debian project.[109]
Debian offers DVD and CD images for installation that can be downloaded using BitTorrent or jigdo. Physical discs can also be bought from retailers.[110] The full sets are made up of several discs (the amd64 port consists of 13 DVDs or 84 CDs),[111] but only the first disc is required for installation, as the installer can retrieve software not contained in the first disc image from online repositories.[112]
Debian offers different network installation methods. A minimal install of Debian is available via the netinst CD, whereby Debian is installed with just a base and later added software can be downloaded from the Internet. Another option is to boot the installer from the network.[113]
The default bootstrap loader is GNU GRUB version 2, though the package name is simply grub, while version 1 was renamed to grub-legacy. This conflicts with distros (e.g., Fedora Linux), where grub version 2 is named grub2.
The default desktop may be chosen from the DVD boot menu among GNOME, KDE Plasma, Xfce, LXDE, and LXQt and from special disc 1 CDs.[114][115]
Debian releases live install images for CDs, DVDs and USB thumb drives, for IA-32 and x86-64 architectures, and with a choice of desktop environments. These Debian Live images allow users to boot from removable media and run Debian without affecting the contents of their computer. A full install of Debian to the computer's hard drive can be initiated from the live image environment.[116] Personalized images can be built with the live-build tool for discs, USB drives and for network booting purposes.[117] Installation images are hybrid on some architectures and can be used to create a bootable USB drive (Live USB).[118]
Package management operations can be performed with different tools available on Debian, from the lowest level command dpkg to graphical front-ends like Synaptic. The recommended standard for administering packages on a Debian system is the apt toolset.[119]
dpkg provides the low-level infrastructure for package management.[120] The dpkg database contains the list of installed software on the current system. The dpkg command tool does not know about repositories. The command can work with local .deb package files, and information from the dpkg database.[121]
An Advanced Packaging Tool (APT) allows a Debian system to retrieve and resolve package dependencies from repositories. APT tools share dependency information and cached packages.[119]
GDebi is an APT tool which can be used in command-line and on the GUI.[122] GDebi can install a local .deb file via the command line like the dpkg command, but with access to repositories to resolve dependencies.[123] Other graphical front-ends for APT include Software Center,[124] Synaptic[125] and Apper.[126]
GNOME Software is a graphical front-end for PackageKit, which itself can work on top of various software packaging systems.
The Debian Free Software Guidelines (DFSG) define the distinctive meaning of the word "free" as in "free and open-source software".[127] Packages that comply with these guidelines, usually under the GNU General Public License, Modified BSD License or Artistic License,[128] are included inside the main area;[129] otherwise, they are included inside the non-free and contrib areas. These last two areas are not distributed within the official installation media, but they can be adopted manually.[127]
Non-free includes packages that do not comply with the DFSG,[130] such as documentation with invariant sections and proprietary software,[131][132] and legally questionable packages.[130] Contrib includes packages which do comply with the DFSG but fail other requirements. For example, they may depend on packages which are in non-free or requires such for building them.[130]
Richard Stallman and the Free Software Foundation have criticized the Debian project for hosting the non-free repository and because the contrib and non-free areas are easily accessible,[9][133] an opinion echoed by some in Debian including the former project leader Wichert Akkerman.[134] The internal dissent in the Debian project regarding the non-free section has persisted,[135] but the last time it came to a vote in 2004, the majority decided to keep it.[136]
The most popular optional Linux cross-distribution package manager are graphical (front-ends) package managers. They are available within the official Debian Repository but are not installed by default. They are widely popular with both Debian users and Debian software developers who are interested in installing the most recent versions of application or using the cross-distribution package manager built-in sandbox environment. While at the same time remaining in control of the security.[137][138]
Four most popular cross-distribution package managers, sorted in alphabetical order:
Three branches of Debian (also called releases, distributions or suites) are regularly maintained:[139]
Other branches in Debian:
The snapshot archive provides older versions of the branches. They may be used to install a specific older version of some software.[143]
Stable and oldstable get minor updates, called point releases; as of August 2021[update], the stable release is version 11.7,[144] released on April 29, 2023 , and the oldstable release is version 10.10.[145]
The numbering scheme for the point releases up to Debian 4.0 was to include the letter r (for revision)[146] after the main version number and then the number of the point release; for example, the latest point release of version 4.0 is 4.0r9.[147] This scheme was chosen because a new dotted version would make the old one look obsolete and vendors would have trouble selling their CDs.[148]
From Debian 5.0, the numbering scheme of point releases was changed, conforming to the GNU version numbering standard;[149] the first point release of Debian 5.0 was 5.0.1 instead of 5.0r1.[150] The numbering scheme was once again changed for the first Debian 7 update, which was version 7.1.[151] The r scheme is no longer in use, but point release announcements include a note about not throwing away old CDs.[152]
Debian has two logos. The official logo (also known as open use logo
) contains the well-known Debian swirl
and best represents the visual identity of the Debian Project. A separate logo also exists for use by the Debian Project and its members only.[153]
The Debian "swirl" logo was designed by Raul Silva[154][155] in 1999 as part of a contest to replace the semi-official logo that had been used.[156] The winner of the contest received an @Debian.org email address, and a set of Debian 2.1 install CDs for the architecture of their choice. Initially, the swirl was magic smoke arising from an also included bottle of an Arabian-style genie presented in black profile, but shortly after was reduced to the red smoke swirl for situations where space or multiple colours were not an option, and before long the bottle version effectively was superseded[disputed – discuss]. There has been no official statement from the Debian project on the logo's meaning, but at the time of the logo's selection, it was suggested that the logo represented the magic smoke that made computers work.[157][158][159]
One theory about the origin of the Debian logo is that Buzz Lightyear, the chosen character for the first named Debian release, has a swirl in his chin.[160][161] Stefano Zacchiroli also suggested that this swirl is the Debian one.[162] Buzz Lightyear's swirl is a more likely candidate as the codenames for Debian are names of Toy Story characters. The former Debian project leader Bruce Perens used to work for Pixar and is credited as a studio tools engineer on Toy Story 2 (1999).
Hardware requirements are at least those of the kernel and the GNU toolsets.[163] Debian's recommended system requirements depend on the level of installation, which corresponds to increased numbers of installed components:[164]
The real minimum memory requirements depend on the architecture and may be much less than the numbers listed in this table. It is possible to install Debian with 170 MB of RAM for x86-64;[164] the installer will run in low memory mode and it is recommended to create a swap partition.[114] The installer for z/Architecture requires about 20 MB of RAM, but relies on network hardware.[164][165] Similarly, disk space requirements, which depend on the packages to be installed, can be reduced by manually selecting the packages needed.[164] As of May 2019[update], no Pure Blend exists that would lower the hardware requirements easily.[166]
It is possible to run graphical user interfaces on older or low-end systems. However, the installation of window managers instead of desktop environments is recommended, as desktop environments are more resource intensive. Requirements for individual software vary widely and must be considered, with those of the base operating environment.[164]
As of the upcoming Trixie release[update], the official ports are:[167]
Unofficial ports are available as part of the unstable distribution:[167]
Debian supports a variety of ARM-based NAS devices. The NSLU2 was supported by the installer in Debian 4.0 and 5.0,[174] and Martin Michlmayr is providing installation tarballs since version 6.0.[175] Other supported NAS devices are the Buffalo Kurobox Pro,[176] GLAN Tank, Thecus N2100[177] and QNAP Turbo Stations.[176]
Devices based on the Kirkwood system on a chip (SoC) are supported too, such as the SheevaPlug plug computer and OpenRD products.[178] There are efforts to run Debian on mobile devices, but this is not a project goal yet since the Debian Linux kernel maintainers would not apply the needed patches.[179] Nevertheless, there are packages for resource-limited systems.[180]
There are efforts to support Debian on wireless access points.[181] Debian is known to run on set-top boxes.[182] Work is ongoing to support the AM335x processor,[183] which is used in electronic point of service solutions.[184] Debian may be customized to run on cash machines.[185]
BeagleBoard, a low-power open-source hardware single-board computer (made by Texas Instruments) has switched to Debian Linux preloaded on its Beaglebone Black board's flash.
Roqos Core, manufactured by Roqos, is a x86-64 based IPS firewall router running Debian Linux.
General Resolution | |||||||||||||||
elect↓ | override↓ | ||||||||||||||
Leader | |||||||||||||||
↓appoint | |||||||||||||||
Delegate | |||||||||||||||
↓decide | |||||||||||||||
Developer | propose↑ | ||||||||||||||
Debian's policies and team efforts focus on collaborative software development and testing processes.[7] As a result, a new major release tends to occur every two years with revision releases that fix security issues and important problems.[146][65] The Debian project is a volunteer organization with three foundational documents:
Year | DD | ±% |
---|---|---|
1999 | 347 | — |
2000 | 347 | +0.0% |
2001 | ? | — |
2002 | 939 | — |
2003 | 831 | −11.5% |
2004 | 911 | +9.6% |
2005 | 965 | +5.9% |
2006 | 972 | +0.7% |
2007 | 1,036 | +6.6% |
2008 | 1,075 | +3.8% |
2009 | 1,013 | −5.8% |
2010 | 886 | −12.5% |
2011 | 911 | +2.8% |
2012 | 948 | +4.1% |
2013 | 988 | +4.2% |
2014 | 1,003 | +1.5% |
2015 | 1,033 | +3.0% |
2016 | 1,023 | −1.0% |
2017 | 1,062 | +3.8% |
2018 | 1,001 | −5.7% |
2019 | 1,003 | +0.2% |
2020 | 1,011 | +0.8% |
2021 | 1,018 | +0.7% |
2022 | 1,023 | +0.5% |
2023 | 996 | −2.6% |
2024 | 1,010 | +1.4% |
Source: Debian Voting Information |
Debian developers are organized in a web of trust.[186] There are at present[update] about one thousand active Debian developers,[187][188] but it is possible to contribute to the project without being an official developer.[189]
The project maintains official mailing lists and conferences for communication and coordination between developers.[129][190] For issues with single packages and other tasks,[191] a public bug tracking system is used by developers and end users. Internet Relay Chat is also used for communication among developers[129] and to provide real time help.[192]
Debian is supported by donations made to organizations authorized by the leader.[33] The largest supporter is Software in the Public Interest, the owner of the Debian trademark, manager of the monetary donations[193] and umbrella organization for various other community free software projects.[194]
A Project Leader is elected once per year by the developers. The leader has special powers, but they are not absolute, and appoints delegates to perform specialized tasks. Delegates make decisions as they think is best, taking into account technical criteria and consensus. By way of a General Resolution, the developers may recall the leader, reverse a decision made by the leader or a delegate, amend foundational documents and make other binding decisions.[33] The voting method is based on the Schulze method (Cloneproof Schwartz Sequential Dropping).[34]
1993 — – 1994 — – 1995 — – 1996 — – 1997 — – 1998 — – 1999 — – 2000 — – 2001 — – 2002 — – 2003 — – 2004 — – 2005 — – 2006 — – 2007 — – 2008 — – 2009 — – 2010 — – 2011 — – 2012 — – 2013 — – 2014 — – 2015 — – 2016 — – 2017 — – 2018 — – 2019 — – 2020 — – 2021 — – 2022 — – 2023 — – 2024 — – 2025 — | Wichert Akkerman Ben Collins Branden Robinson Anthony Towns Steve McIntyre Lucas Nussbaum Neil McGovern Mehdi Dogguy Sam Hartman Jonathan Carter Andreas Tille | |
Project leadership is distributed occasionally. Branden Robinson was helped by the Project Scud, a team of developers that assisted the leader,[196] but there were concerns that such leadership would split Debian into two developer classes.[197] Anthony Towns created a supplemental position, Second In Charge (2IC), that shared some powers of the leader.[198] Steve McIntyre was 2IC and had a 2IC himself.[199]
One important role in Debian's leadership is that of a release manager.[200] The release team sets goals for the next release, supervises the processes and decides when to release. The team is led by the next release managers and stable release managers.[201] Release assistants were introduced in 2003.[202]
The Debian Project has an influx of applicants wishing to become developers.[203] These applicants must undergo a vetting process which establishes their identity, motivation, understanding of the project's principles, and technical competence.[204] This process has become much harder throughout the years.[205]
Debian developers join the project for many reasons. Some that have been cited include:
Debian developers may resign their positions at any time or, when deemed necessary, they can be expelled.[33] Those who follow the retiring protocol are granted the "emeritus" status and they may regain their membership through a shortened new member process.[211]
upstream | |||
↓ | packaging | ||
package | |||
↓ | upload | ||
incoming | |||
↓ | checks | ||
unstable | |||
↓ | migration | ||
testing | |||
↓ | freeze | ||
frozen | |||
↓ | release | ||
stable | |||
Each software package has a maintainer that may be either one person or a team of Debian developers and non-developer maintainers.[212][213] The maintainer keeps track of upstream releases, and ensures that the package coheres with the rest of the distribution and meets the standards of quality of Debian. Packages may include modifications introduced by Debian to achieve compliance with Debian Policy, even to fix non-Debian specific bugs, although coordination with upstream developers is advised.[211]
The maintainer releases a new version by uploading the package to the "incoming" system, which verifies the integrity of the packages and their digital signatures. If the package is found to be valid, it is installed in the package archive into an area called the "pool" and distributed every day to hundreds of mirrors worldwide. The upload must be signed using OpenPGP-compatible software.[129] All Debian developers have individual cryptographic key pairs.[214] Developers are responsible for any package they upload even if the packaging was prepared by another contributor.[215]
Initially, an accepted package is only available in the unstable branch.[129] For a package to become a candidate for the next release, it must migrate to the Testing branch by meeting the following:[216]